Question

我正在试图找出我的代码有什么问题。任何人都可以解决它吗？

def main():
   fname = input("Enter filename:")
   infile = open(fname, "r")
   SD()

def SD():
  b= []
  a = 5.0 
  r = len(b) 
  for n in range(r-1):
      b.append((r[n] -a)**2)
  m = (float(b)/r)**0.5
  print("The standard deviation is", m)
main()

Answer 1

你有一些错误：

def SD():

  # b is empty
  b= []
  a = 5.0 

  #this will always be 0
  r = len(b) 

  # range(r-1) == [] because it is range(-1)
  # whole loop is skipped
  for n in range(r-1):
      b.append((r[n] -a)**2)

  # float(b) should throw an error, maybe sum(b) ?
  m = (float(b)/r)**0.5
  print("The standard deviation is", m)
main()

b是一个列表;你不能把一个列表放到浮点数中。

也许您想将数组传递给SD()？你应该read()文件内容然后split()进入数组并将其作为参数传递给SD（）（你将在其上调用int()。）

Answer 2

样本：

def SD(numList):
    cntN=len(numList)
    sumN=0
    for i in numList:
        sumN+=i
    avgVal=float(sumN)/float(cntN)
    sumVar=0.0
    for i in range(cntN):
        sumVar+=float((numList[i]-avgVal)**2)
    return ((float(sumVar)/float((cntN-1)))**0.5)

开始Python打印出标准偏差

2 个答案: